Is it three hours? I'll update the OP if you're sure.
Absolutely 100% dead sure. Trust me. It's three hours, one hour per day.
Link can play the Inverted Song of Time to slow the flow of time which will slow it down to 150 seconds (two and a half minutes) for each game hour, exactly three hours for an entire cycle.[6]
You need to change the OP as you are making it sound worse than it is